This invention relates generally to integrated circuits and more particularly to enabling a stand-alone integrated circuit.
Integrated circuits are known to include a large amount of circuitry in a very small area. The circuitry may perform a wide variety of functions such as a microprocessor, digital signal processor, operational amplifier, integrator, audio encoder, audio decoder, video encoder, video decoder, et cetera. To power such integrated circuits, the integrated circuits include power pins for a power input (typically Vdd) and a return pin (typically Vss). The power is typically provided by a regulated external power supply. As such, once the external power supply is up and running, the integrated circuit may be activated in a known state.
For most digital circuits on an integrated circuit, a clock signal is needed. The clock is typically generated once an external power supply is producing a regulated supply voltage to the integrated circuit (IC) and the IC has been activated. To ensure that the digital circuitry begins functioning in a known state, it is important to delay activation of the digital circuit until the power supply is producing a stable supply voltage and the clock is operating properly. Once these operating parameters are ensured, the digital circuitry may be activated.
Insuring the proper enablement of an IC is relatively straightforward when the power supply is external to the IC. If, however, the power converter is on-chip with the digital circuitry and the power converter requires a clock signal to produce a supply voltage, a difficulty arises in enabling such a stand-alone integrated circuit.
Therefore, a need exists for a method and apparatus for enabling a stand-alone integrated circuit that includes an on-chip power converter.